How to Test a Samsung Dishwasher Thermistor

Samsung uses an NTC thermistor, so its resistance falls as temperature climbs. When it fails, the board gets a false reading and either shuts the heater off early (cold water, a 5E code) or leaves it on too long. Because the sensor is far cheaper than the heater, test it first: a good element reads about 10-15 ohms, so if that checks out the sensor is the likely fault.

Before you start#

Safety warning: Disconnect power at the circuit breaker. The thermistor operates on low voltage from the control board, but other components in the same area carry 120V AC. Always verify power is disconnected before reaching into the sump area.

Test it before you replace it#

Room-temperature resistance#

Kill power, pull the kick plate (two Phillips screws and two clips), and find the thermistor probe in the sump near the heater terminals. Unplug its two-wire connector, set the meter to the 200K range, and read across the pins. A working sensor reads about 50K ohms at room temperature (77F/25C), with 40K-60K acceptable. A reading under 10K, over 200K, or open means it has failed.

Response to heat#

If the room reading is borderline, warm the probe tip with a hair dryer for 30 seconds and read again — it should drop noticeably, toward 20-30K. A thermistor that ignores temperature has failed internally.

Wiring continuity#

If the sensor tests good but 5E persists, put the meter on continuity and check each wire from the sensor connector back to the board. A broken wire mimics a dead sensor.

Replacing the thermistor#

1. Kill power and open up#

Switch off the breaker, wait a couple of minutes, and remove the kick plate as above.

2. Free the probe#

Trace the two wires to their connector (usually within 6-8 inches), press the tab, and separate it. The probe is held by a rubber grommet, a plastic clip, or occasionally a small screw — pull it straight out of the grommet, depress the clip tab, or remove the screw as your model dictates.

3. Check the mounting point#

Inspect the grommet or hole for scale and damage. A hardened or cracked grommet must be replaced with the sensor, or ordered separately, so water cannot weep from the sump through the probe hole.

4. Fit the new sensor#

Push the new probe in until its tip reaches the same depth into the sump as the old one (about 1/2 to 3/4 inch) and sits in the water flow path — if it only meets air, it reads ambient and throws false 5E errors.

5. Reconnect and verify#

Clip the connector home and route the wires clear of the hot heater terminals. Before refitting the kick plate, meter the new sensor through its connector to confirm about 50K ohms and good wiring, then run a wash cycle and watch that the temperature climbs and no 5E appears (SmartThings will show a steady rise from roughly 70F to 130-140F).

Samsung NTC resistance reference#

Readings within 10-20% of these still indicate a working sensor.

When to call a professional#

EasyBear technicians serving Sacramento and the Bay Area carry Samsung-specific diagnostic tools and replacement parts on every service call. Call one if both the sensor and element test good yet 5E persists (a board fault), if you cannot find the probe, if the harness is corroded, or if water leaks from the mounting point after the swap.

Need Professional Help?#

• Dishwasher repair service
• Samsung appliance repair
• Dishwasher repair cost guide

Done troubleshooting? If the issue persists, let an EasyBear tech take a look — same-day dishwasher repair in Sacramento and the Bay Area.